15.1 Lateral Cervical Region

Question 1

Identify the platysma. This muscle is continuous with what fascial layer? Describe its innervation.

Answer 1

The platysma muscle originates and lies within the superficial fascia.
It is innervated by the Cervical Branch of the Facial Nerve (CN VII).

Question 2

Identify and describe the investing layer of the deep cervical fascia.

Answer 2

splits to enclose the trapezius and SCM muscles (muscles innervated by CN XI).

Question 3

Identify the sternoclidomastoid muscle and describe its attachments, function, and innervation.

Answer 3

• Attaches from sternum and clavicle to mastoid process.
• Function: Bilateral contraction flexes the head, while unilateral contraction rotates head to the same side (ipselateral).
• innervation: CN XI

Question 4

Identify the external jugular vein and describe its course.

What areas does this drain and where does it terminate?

Answer 4

• Pierces out from Carotid/Investing Fascia, Passess over SCM
• Receives blood from exterior cranium and deep face. Drains into subclavian vein.

Question 5

Identify and describe “Erb’s Point”

Answer 5

-The site roughly midway along the posterior aspect of the SCM where cutaneous branches of the cervical plexus emerge.

Question 6

Identify and Name the 4 cutaneous branches of the cervical plexus emerging from Erb’s point. Describe their course and spinal contribution.

Answer 6

• the supraclavicular nerves (C3-C4), composed of lateral, intermediate and medial groups passing inferiorly toward the clavicle
• the lesser occipital nerve (C2), passing superiorly along the posterior border of the sternocleidomastoid
• the great auricular nerve (C2-C3), passing superiorly and superficial to sternocleidomastoid, and
• the transverse cervical nerve (C2-C3), passing transversely over sternocleidomastoid toward the anterior aspect of the neck (see Table 2)

Question 7

Identify the inferior belly of the omohyoid muscle. Describe its attachments, function, and innervation.

Answer 7

• Originates from the superior border of the scapula and inserts onto the hyoid bone.
• Function: The omohyoid acts to depress the hyoid and to draw the larynx and hyoid bone down for phonation and swallowing.
• Innervation: Ansa cervicalis of cervical plexus (C1 to C3).

Question 8

The Posterior triangle can be further subdivided into what 2 triangles by the inferior belly of the omohyoid muscle.
-Identify these 2 triangles and their contents:

Answer 8

• Omoclavicular triangle: subclavian artery, subscapular artery, supraclavicular nerve.
• Occipital triangle: Spinal Accessory nerve (CN XI), Trunks of brachial plexus, transverse cervical artery, posterior branches of cervical plexus.

Question 9

Identify the cervical artery and vein in the posterior triangle.

Answer 9

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Question 10

Identify the Accessory Spinal Nerve (CNXI) in this space.

Answer 10

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Question 11

Identify and describe the pre vertebral layer of deep cervical fascia

Answer 11

• Located deep in the neck surrounding the vertebral column and associated muscles (splenius, levator scapulae, scalenes, longus coli and capitis muscles).
  1. It extends from the base of the skull into T3 where it blends with the anterior longitudinal ligament. Laterally it extends as the axillary sheath down into the upper limb.
  2. The sympathetic trunk and the roots of the brachial plexus are embedded within in this layer.
  3. Infection within the fascia may extend laterally into the neck and cause swelling behind the SCM
  4. Infection can spread into the retropharyngeal space anteriorly producing a bulge in the pharynx that may cause difficulty swallowing and speaking. Infection in this space can also spread inferiorly into the mediastinum.

Question 12

Identify the anterior, middle, and posterior scalene muscles. Describe their attachments, function, and innervation.

Answer 12

-Attach between transverse processes of the spine
-Fxn: Anterior functions to flex head bi-laterally, and all three do lateral flexion uni-laterally. Also important as secondary muscles of respiration.
-Innervated by anterior rami of C2-C8 depending on associated spinal levels.
Note the brachial plexus and subclavian pass between the anterior and middle scalene.

Question 13

Identify the Levator scapulae muscle. Describe its attachments, function, and innervation.

Answer 13

• Originates from the transverse processes of C1 to C4 and inserts onto the superior angle of the scapula.
• Fxn: draw the scapula medially upward while moving the inferior angle of the scapula medially and to incline the neck to the same side.
• Innervation: Dorsal scapular nerve (C4 and C5).

Question 14

Identify the splenius capitis and cervices muscles. Describe their attachments, function, and innervation.

Answer 14

• The splenius capitis originates from the ligamentum nuchae and the spinous processes of C7 to T3 and inserts onto the lateral superior nuchal line of the occipital bone and the mastoid process of the temporal bone.
• The splenius cervicis originates from the spinous processes of T3 to T6 and inserts onto the transverses processes of C1 and C2.

-Act bilaterally to extend the cervical spine and head.
unilaterally to flex and rotate the head to the same side.

-Innervation: Spinal nerves C1-C6 (posterior rami, lateral branches).

Question 15

Identify the phrenic nerve in this area.

Answer 15

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